Es’hail 2 / QO-100

Today, construction, calibration helix antenna for contact up Link 2.4 GHz with the geostationary Amateur Radio satellite Es'hail 2 / QO-100 .

And comparison with Bamatech dual feed. (Well pleased, my Helix antenna homemade have a Forward reflection = -42 dBm, antenna Bamatech dual feed = -32 dBm ...

Return loss = -42 dBm
VSWR = 1.016 /1
Reflection coefficient = 0.008

Unless an error on my part, I calculate the helix like this:
Dish : diameter (mm): 730 x 800
focal distance (mm): 530
F/D Ratio: 0.64
f/D x10 = turns. Offset f/D 0.6.  =  6 turns

So OK for service.. Soon ready for contacts.Preparation / setting up, up converter DX patrol 432Mhz / 2.4 GHz / PA 4 w / OCXO 10 Mhz / Circulator / bandpass filter.
Down Link 10 Ghz good reception with dish ofset 70 cm /  Modified LNB PLL twin Octagon  Green HQ / SDR RSP2 / Software SDR Play 3.09.

 

 

 

Just to compare Bamatech dual feed = -32 dBm .

So My Helix seem good.

 

 On the bench.

Preparation / setting up, up converter DX patrol 432Mhz / 2.4 GHz / PA 4 w / OCXO 10 Mhz / Circulator / bandpass filter.

Will see...

 Updated on time ......see U. 73

later this night.. retuning a bandpass filter for QO-100

Very sharp !

 

26 June 2019
Boxed finished (UP converter 432 Mhz / 2.4 Ghz + Amplifier 4 w)  installed near the dish.Next step, Due to the drift of the LNB despite it is with a  PLL, (the frequency is not enough stable), I must build  a 25 Mhz TCX0 controlled by my10 Mhz GPS.
                                                                             READY....

 

 Problems with my Hélix.

Do not laugh! Now, during the winter, too much rain  and it disturbs the performance of my Helix antenna.
In the emergency, I installed temporarily this protection .. Now it's safe.

But. not satisfied. built a waterproof new one 

remains to put the LNB

                                                                     Ready ...

Tower project

On the way for the construction of my tower.
Height: 15m – Base square section of 65 x 65 cm
Last year 2017, I finished the construction of my freestanding tower of 15m.
(The trolley is also on the way).
Finally, this week, I was finally able to finish the construction of the chair that will go into the concrete.
The formwork is 1.5m X 1.5m X 1.7m. - 90cm of earth and 60cm of rock made with the jackhammer!! And 20cm of formwork wood), about 6500 kg of concrete.
Fixation of the base plate in the concrete with 8 rods of 26mm diameter, length 1,4m.
Fixation of the tower on the base plate with 13 rods of 20mm diameter.
In case of very big wind!! (Sometime 80/90 km/h) 4 x 3m supports will be attached to the concrete diagonally at the 4 corners of the tower and 4 concrete blocks are provided for guying if necessary. It will should not move ...Hi
Today, 23/11, the concrete is finished. This project progressing slowly but surely.
(soon I'll add some pics of the trolley)

New Satellites antennas Setup

Sweat to make the antennas .. Finally, Ready to chasing satellites. 1st tests conclusive on 2m/70cm.. 23cm later !
2m cross Yagi and the helix gave me a lot of mods, settings and mechanics, finally it's over!
Seems to work fine. Contacted easily couple of satellites. 1st longs distances was on AO-7 mode B with:
- PT2AP grid square GH51JO at 6822 km. 06 April 2018
- PY2LN, grid square GG66PK at 6326 km. 20 May 2108

Will see to add somes preamp. and connect to test the 23cm yagi's soon.

Yagi antenna 35 el. 23CM

 Inspired by DL6WU, F9FT, DJ9YW

Always for the Fun and for some tests with the Satellites, I continued the construction of my antennas for the 1296 Mhz with the construction of some Yagis 35 elements. I did not want the elements to cross or be in contact with the boom, I chose the isolated version.
And 35 elements only on a boom of about 3m gives a gain of about 17.8 dBd. Sufficient for me between the ratio of the gain and the length of the boom.
I was inspired by the model and design of F9FT 23cm / 35el., But I built the dipole is symmetrical T rather than a Loop trombone.
To install the distant elements of the boom, I made some tests with supports like Y nylon columns  and  square support used to fix the ties wraps but it was inconclusive.
Having nothing else, I looked on the Web, supports already built for this kind of application at I0JXX.

Here are the references:
http://www.i0jxx.com/en/52-4mm

ISO15 4
Element diameter 4 mm Boom dimension 15 x 15 mm Distance from boom 40 mm
BOX4JXX
Nylon 6.6 box, it can be bored in order to put in dipoles and connector

Elements: 4mm diameter aluminum rod
Boom: 15mm square, length: 3m

This antenna is easy to build, the only care is the strict respect and the precision of the dimensions. I used EZNEC software - RF SIM 99 - Yagi Calculator by John Drew VK5DJ.

H Pattern

V Pattern

Ready for connection and First Tests.

Next descriptions: 4x12 el. 144Mhz, 4 x 25 el. 432Mhz, Mesh dish 3,2m F / d: 0.4

145Mhz Cross Yagi

2 x 10 el cross yagi 145 MHz. RHCP.
Feed system: adaptation of the dipole in T symmetrical match

The procedure is easy to take all elements and mount them at 90 degree angle on the same boom.
Traditionally circular polarization is generated by feeding two crossed dipoles 90 degrees out off phase. But you can also shift the dipoles 90 degrees in space and feeding then in-phase with the same effect. The advantage is that the two cables in the splitter have equal length and therefore gives identical transformation of antenna impedance
I prefer the mechanical method despite the electrical method (with different length of cable to obtain the 90 deg phase angle). So, I have shifted each V element exactly at ¼ Lambda forward on the boom. So the entire vertical antenna is shifted forward with reference to the horizontal antenna.
The forward shift (Offset) between the two dipoles is 517 mm to obtain 90 deg Phase angle.

Like this the two antennas are excited with a 90 degr. of phase shift. With this now a rotating field is radiated.
By shifting one section of the yagi forward by a quater wavelength the phasing cable to the two antennas becomes equal, impedances becomes equal and the antennas must share the power equally - regardless of the VSWR.
The two antennas must be feed with a splitter. An air line gives by the calculation an impedance of 35,35 ohms : 𝑍𝜆4⁄∗1√𝜀𝑟 =√𝑍𝑝∗𝑍0∗ 1√1 =√25∗50 ∗1= √1250=35,35𝛺
But mechanical splitter is too big at this frequency.
So the splitter can be made from two 75 ohm ¼ lambda equal length of coax cable.

On 144 MHz a quater wavelength coax is 1/4 x 300/144 x 0,66 = 340 mm (the real velocity factor of the coax used must be applied . In this case + 0.66, solid polyethylene dielectric).  I use three quater wavelength 75 ohm cable, which gives the same transformation. The cable length of 102 cm allows the point where the three coax ends are joined together far from the dipoles.
Software: For Yagi antenna, I use the VK5DJ John Drew software ‘’Yagi calculator’’ of http://www.vk5dj.com/yagi.html